A break in a major water line Tuesday blasted a man-size hole in Cohn Street and left many thousands of Uptown New Orleanians under a boil-water advisory that's expected to last well into Wednesday.

Sewerage and Water Board crews had finally cleared the
street of the majority of water and debris by about 5 p.m. Shortly after, a large jack
hammer began drilling into the center of Cohn Street to gain full access to the
damage piped, which is estimated to be about 80 years old, and began the task
of securing the area around the pipe so repair work could begin.

Joe Becker, S & WB superintendent, said he expects the
repair to take 1-2 days and crews will work from sunup until sundown.

"Once the repairs are complete things are going to have dry
out a bit before the street can be repaved. It could be very dangerous to
immediately pave over an area that took on so much water. We could be looking at
over a week before the entire project is complete."

Becker stressed all residents in the immediate vicinity of
the water main break have water and are not under the boil water advisory. The
pipe that broke is a feeder pipe to other parts of the Uptown and surrounding areas.

But residents who own vehicles that sustained damage during
the street flooding will have other headaches to deal with.

Amanda Bray's Mini-Cooper took on water this morning as she
was preparing to go to work. As of about 5:30 p.m. the car still wouldn't
start. Bray said she had not yet contacted her insurance company, hoping her
car would dry out and start as the day wore on.

"I'm not sure if it's the electrical system or what at this
point. The water it took on went up to the bottom of the driver's seat. I have
no idea how the insurance company will handle a situation like this."

The rupture in the 30-inch pipe occurred before dawn Tuesday, but the Sewerage & Water Board didn't warn residents and businesses until nearly noon not to drink, bathe, shower or wash their food in tap water without boiling it first. Echoing explanations from past water emergencies, officials said they delayed issuing an immediate warning so that they could first balance the break's threat to public safety against the public inconvenience of a boil-water warning.

"This is highly precautionary," S&WB Executive Director Marcia St. Martin said, "and it's a balance between customer service, customer inconvenience, inconvenience to residents, inconvenience to businesses and balancing public health at the same time."

More than 24,000 S&WB customers living or working between South Carrollton and Jackson avenues and south of Maple and Loyola streets should continue to boil all potable water for the next 24 hours, officials said Tuesday afternoon.

Boil-water orders and advisories in New Orleans have been happening more frequently in the past few years than ever before in memory -- a result of the S&WB's aging system of pipes and the damage wrought by Hurricane Katrina and the floodwaters that followed.

Water pressure in parts of the Carrollton neighborhood dropped precipitously around 5:30 a.m. Tuesday, according to some residents. About a half hour later, the S&WB recorded a spike in demand for water at its east bank water treatment plant. It sent crews to investigate as complaints began to come in that a hole had opened up in the middle of the 7800 block of Cohn, three blocks off South Carrollton.

Residents awoke to discover parts of Cohn, Burdette, Fern and other nearby streets submerged under as much as two feet of gushing water. S&WB workers began shutting off valves, but they didn't have any understanding of how low the pressure had dropped in the broken line, which is responsible for transporting potable water as far away as the Irish Channel, until 7:30 a.m., St. Martin said. It took four more hours to analyze the data, she said.

State water safety standards require the S&WB to issue boil-water warnings if the pressure in the system, which normally is about 60 pounds per square inch, drops to 15 psi. St. Martin said pressure readings -- which are taken at 30 fire stations throughout the city -- never dropped below 16 psi, leaving officials in a quandary.

"We could not determine that, from the time of the initial break until those readings were taken ... if anyone in the immediate vicinity of the transmission main would have possibly had a drop in water pressure below 15 psi," she said.

The S&WB issued the boil-water advisory for neighborhoods closer to the Mississippi River that were fed by the pipe that broke. The list didn't include those streets immediately around the site of the break.

With a boil-water advisory in place, scientists with the Louisiana Department of Health and Hospitals collected water samples from 10 nearby locations. They were placed in an incubator around 3:30 p.m. and will remain under observation for at least 24 hours to see whether any harmful bacteria begin to grow.

While the situation appeared under control by midafternoon Tuesday, water still trickled within the hole and much of Cohn Street was covered with sunbaked mud and gravel. The scuffing sound of shovels against pavement rang down the block as cleanup crews cleared the street of debris. Some puddles remained, the last of what St. Martin described as "millions and millions of gallons of water" that had inundated the neighborhood.

A partially submerged car parked directly above the break had to be towed away to let crews access the damaged pipe.

St. Martin said it could take several hours to excavate the hole and assess the damage before the S&WB can determine what led to the rupture. While she said she didn't know the age of that particular pipe, she noted that most of the city's water distribution network is well over a half-century old.

Tuesday's boil-water advisory affected a much smaller swath of New Orleans than the last two major directives, which touched the entire east bank of the city. Problems at the S&WB's Carrollton power plant, rather than an isolated water main break, led to those broader warnings in March and October.

In all, the city has endured at least a half dozen boil-water advisories or orders since Katrina.

A complete renovation of the city's water, sewer and drainage systems could cost as much as $3.3 billion. Mayor Mitch Landrieu's administration has started to move on a major overhaul of the power plant, financed by $141 million in federal hazard mitigation grant dollars.